1. Field of the Invention
The present invention relates to organic light-emitting display devices. More particularly, the invention relates to packaging of organic light-emitting display devices.
2. Description of the Related Art
In general, an organic light-emitting display device comprises a first substrate comprising a pixel region and a non-pixel region and a second substrate opposed and disposed to the first substrate and bonded to the first substrate with sealant such as epoxy for encapsulation.
In the pixel region of the first substrate a plurality of organic light-emitting diodes are formed at intersecting portions of scan lines and data lines in the form of a matrix. Each organic light-emitting diode comprises i) an anode electrode, ii) a cathode electrode and iii) an organic thin film layer. The organic thin film layer may comprise a hole transporting layer, the cathode electrode, a light-emitting layer, and an electron transporting layer. The organic thin film layer may be formed between the anode electrode and the cathode electrode.
Since the organic light-emitting diode includes organic material, it is vulnerable to degradation in the presence of oxygen. Further, since the cathode electrode is made of metal material, it may be oxidized by moisture in the air so as to degrade its electrical characteristic and light-emitting characteristics. To prevent this, a moisture absorbent material is mounted on a container, e.g., manufactured in the form of a can or cup made of metal material, or on a second substrate of organic, plastic, etc., in the form of powder, or adhered thereto in the form of a film, thereby removing moisture that penetrates from the surroundings.
However, the method of mounting the moisture absorbent material in the form of powder can cause problems such as complicating the process, increasing material and process costs, increasing the thickness of a display device, and being difficult to apply to a top emitting (front light-emitting) display configuration. Also, the method of adhering moisture absorbent material in the form of a film can cause problems in that it is limited in its ability to remove moisture and it is difficult to apply to mass production due to low durability and reliability.
Therefore, in order to solve such problems, there has been proposed a method of encapsulating an organic light-emitting display device by forming a sidewall with frit. Typically, the frit forming process includes inserting a substrate into a chamber and irradiating the substrate with a laser beam or infrared rays, thereby bonding the frit to the substrate. However, when the substrate is inserted into the chamber, since heat is transferred to the overall area of the substrate, the thin film transistor and the organic light-emitting diode formed on the substrate are at risk of being damaged.
The discussion of this section is to provide a general background of organic light-emitting devices and does not constitute an admission of prior art.